Light source apparatus and sensing module

ABSTRACT

A suppression of a rise in temperature is to be attained for a light source apparatus provided with an emission section in which a plurality of vertical-cavity surface-emitting laser light-emitting elements is arrayed. A light source apparatus according to the present technology includes an emission section in which a plurality of vertical-cavity surface-emitting laser light-emitting elements is arrayed, and a driving section configured to cause the plurality of light-emitting elements of the emission section to emit light, in which at least a portion of a region including driving elements in the driving section is disposed so as not to overlap with the emission section.

TECHNICAL FIELD

The present technology relates to a light source apparatus provided withan emission section in which a plurality of vertical-cavitysurface-emitting laser light-emitting elements is arrayed, and a sensingmodule provided with an image sensor that captures an image by receivinglight that is emitted by the emission section and then reflected by asubject.

BACKGROUND ART

The vertical-cavity surface-emitting laser (VCSEL) is known as alight-emitting element that emits laser light, as described by PatentLiteratures 1 and 2 below, for example.

A VCSEL light-emitting element is configured such that an oscillator isformed perpendicular to the semiconductor substrate surface and laserlight is emitted in the perpendicular direction, and in recent years,VCSELs have been used widely as light sources when measuring thedistance to a subject according to a structured light (STL) method and atime of flight (ToF) method, for example.

CITATION LIST Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2012-195436-   Patent Document 2: Japanese Patent Application Laid-Open No.    2015-103727

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Here, in the case of measuring the distance to a subject according to anSTL method or a ToF method, a light source in which a plurality of VCSELlight-emitting elements is disposed in a two-dimensional array is used.Specifically, the subject is illuminated with light emitted from theplurality of light-emitting elements, and the distance to the subject ismeasured on the basis of an image obtained by receiving reflected lightfrom the subject.

When measuring distance in this way, the plurality of light-emittingelements is made to emit light, but heat generated by components such asthe driving circuit for causing the light-emitting elements to emitlight causes the temperature of the chip in which the light-emittingelements are formed to rise easily, which may lead to a heat-inducedmalfunction such as a drop in the emission efficiency of thelight-emitting elements. Also, the temperature of the light-emittingelements rises due to emission, and such generated heat may lead todegraded circuit characteristics in the driving circuit that drives thelight-emitting elements.

The present technology has been devised in light of the abovecircumstances, and an object is to attain a suppression of a rise in thetemperature for a light source apparatus provided with an emissionsection in which a plurality of vertical-cavity surface-emitting laserlight-emitting elements is arrayed.

Solutions to Problems

A light source apparatus according to the present technology includes anemission section in which a plurality of vertical-cavitysurface-emitting laser light-emitting elements is arrayed, and a drivingsection configured to cause the plurality of light-emitting elements ofthe emission section to emit light, in which at least a portion of aregion including driving elements in the driving section is disposed soas not to overlap with the emission section.

With this arrangement, the heat generated from the driving elements andtransmitted to the light-emitting elements is reduced. Also, the heatgenerated by the light-emitting elements and transmitted to the drivingcircuit of the driving section is also reduced.

In the light source apparatus according to the present technologydescribed above, it is desirable that a chip in which the emissionsection is formed be mounted onto a chip in which the driving section isformed, and at least a portion of the region including the drivingelements of the driving section be disposed so as not to overlap withthe light-emitting elements of the emission section.

With this arrangement, the leads that connect the emission section andthe driving section can be shortened, and an increase in wiringresistance can be moderated. Also, the region including the drivingelements can be provided at a distance from the light-emitting elementsthat generate heat.

In the light source apparatus according to the present technologydescribed above, it is desirable that the driving section include aplurality of wiring layers in which leads for electrically connectingthe driving elements and the light-emitting elements are formed.

With this arrangement, the leads can be arranged while maintaining thecross-sectional area of the leads, and an increase in wiring resistanceis moderated.

In the light source apparatus according to the present technologydescribed above, it is desirable that the leads be formed such that adistance between the driving elements and the light-emitting elementsconnected to each other is longer in lower wiring layers.

With this arrangement, when drawing out a lead from a lower layer towarda higher layer, it is possible to avoid a situation in which ahigher-layer lead obstructs the drawing-out of the lower-layer lead.

In the light source apparatus according to the present technologydescribed above, it is desirable that a plurality of regions includingthe driving elements be provided in the driving section.

By dividing the region including the driving elements into a pluralityof regions, the lengths of the leads that connect the driving elementsand the light-emitting elements can be shortened.

In the light source apparatus according to the present technologydescribed above, it is desirable that as a length of the leadsincreases, a portion of increased cross-sectional area when taking across section in a plane perpendicular to an extension direction of theleads be formed in the leads.

Because the leads are lengthened due to the increased distance from thedriving elements to the light-emitting elements, the wiring resistanceincreases. For this reason, the cross-sectional area of the leads isincreased to moderate the increase in wiring resistance.

In the light source apparatus according to the present technologydescribed above, it is desirable to increase the width in the thicknessdirection of the wiring layers in the portion of the leads.

By increasing the width in the thickness direction of the wiring layers,the cross-sectional area of the leads increases, and an increase inwiring resistance is moderated.

In the light source apparatus according to the present technologydescribed above, it is desirable to increase the width of the portion ofthe leads in the planar direction of the wiring layers.

By increasing the width in the planar direction of the wiring layers,the cross-sectional area of the leads increases, and an increase inwiring resistance is moderated.

In the light source apparatus according to the present technologydescribed above, it is desirable that the cross-sectional area of theleads provided in the wiring layers be larger in lower wiring layers.

The lower the wiring layer, the greater the distance from the drivingelements to the light-emitting elements, and the leads become longer asa result. With this arrangement, the wiring resistance increases forleads provided in lower layers. For this reason, the cross-sectionalarea of the leads in lower layers is increased to moderate the increasein wiring resistance.

In the light source apparatus according to the present technologydescribed above, it is desirable that the driving section be configuredto be capable of individually driving emission operation for eachpredetermined unit of a plurality of the light-emitting elements.

The predetermined unit may be a unit containing a single light-emittingelement, a unit containing a block of multiple light-emitting elements,or the like.

With this configuration, the emission driving current can be set to turnemission ON/OFF individually for each light-emitting element or in unitsof blocks acting as multiple light-emitting element groups, for example.

In the light source apparatus according to the present technologydescribed above, it is desirable that the emission section be configuredto emit light in synchronization with a frame period of an image sensorconfigured to receive light emitted by the emission section andreflected by a subject.

With this arrangement, to handle the case of measuring distance byilluminating a subject with light emitted by the emission section andreceiving the light with an image sensor, it is possible to cause thelight-emitting elements to emit light at appropriate timings accordingto the frame cycle of the image sensor.

Furthermore, a sensing module according to the present technologydescribed above includes a light source apparatus provided with anemission section in which a plurality of vertical-cavitysurface-emitting laser light-emitting elements is arrayed, and a drivingsection configured to cause the plurality of light-emitting elements ofthe emission section to emit light, in which at least a portion of aregion including driving elements in the driving section is disposed soas not to overlap with the emission section, and an image sensorconfigured to capture an image by receiving light emitted by theemission section and reflected by a subject.

Action similar to the light source apparatus according to the presenttechnology described above are also obtained by such a driving methodand sensing module.

Effects of the Invention

According to the present technology, a suppression of a rise intemperature can be attained for a light source apparatus provided withan emission section in which a plurality of vertical-cavitysurface-emitting laser light-emitting elements is arrayed.

Note that, the effect described here is not necessarily limited, and canbe any effect described in the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of adistance measuring apparatus as an embodiment of a light sourceapparatus according to the present technology.

FIG. 2 is a diagram explaining a technique of measuring distanceaccording to a structured light (STL) method.

FIG. 3 is a diagram illustrating an exemplary circuit configuration ofthe light source apparatus as an embodiment.

FIG. 4 is a diagram illustrating a modification of a driving circuitprovided in the light source apparatus as an embodiment.

FIG. 5 is a diagram illustrating a circuit configuration as amodification of the light source apparatus as an embodiment.

FIG. 6 is a diagram illustrating an exemplary substrate configuration ofthe light source apparatus as an embodiment.

FIG. 7 is a diagram illustrating another exemplary substrateconfiguration of the light source apparatus as an embodiment.

FIG. 8 is a diagram illustrating yet another exemplary substrateconfiguration of the light source apparatus as an embodiment.

FIG. 9 is a diagram illustrating an exemplary arrangement of temperaturesensors provided in the light source apparatus as an embodiment.

FIG. 10 is a diagram illustrating an exemplary structure of an emissionsection provided in the light source apparatus as an embodiment.

FIG. 11 is a diagram illustrating another exemplary structure of anemission section provided in the light source apparatus as anembodiment.

FIG. 12 is a diagram illustrating an arrangement relationship betweenthe emission section and a driving section as an embodiment.

FIG. 13 is a diagram illustrating another arrangement relationshipbetween the emission section and the driving section as an embodiment.

FIG. 14 is a diagram illustrating exemplary arrangements of the emissionsection and the driving section as an embodiment.

FIG. 15 is a diagram illustrating another arrangement relationshipbetween the emission section and the driving section as an embodiment.

FIG. 16 is a diagram for explaining leads that connect the emissionsection and the driving section as an embodiment.

FIG. 17 is another diagram for explaining leads that connect theemission section and the driving section as an embodiment.

FIG. 18 is another diagram for explaining leads that connect theemission section and the driving section as an embodiment.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the attached drawings will be referenced to describeembodiments according to the present technology in the following order.

<1. Configuration of distance measuring apparatus>

<2. Distance measuring techniques>

<3. Circuit configuration related to emission driving>

<4. Variations in substrate configuration>

<5. Exemplary VCSEL structure>

<6. Arrangement relationship between light-emitting elements and drivingtransistors>

<7. Leads that connect light-emitting elements and driving transistors>

<8. Summary of embodiment and modifications>

<9. Present technology>

1. CONFIGURATION OF DISTANCE MEASURING APPARATUS

FIG. 1 illustrates an exemplary configuration of a distance measuringapparatus 1 as an embodiment of a light source apparatus according tothe present technology.

As illustrated in the diagram, the distance measuring apparatus 1 isprovided with an emission section 2, a driving section 3, a power supplycircuit 4, an emission-side optical system 5, an imaging-side opticalsystem 6, an image sensor 7, an image processing section 8, a controlsection 9, and a temperature detection section 10.

The emission section 2 emits light from a plurality of light sources. Asdescribed later, the emission section 2 in this example includesvertical-cavity surface-emitting laser (VCSEL) light-emitting elements 2a as the light sources, and these light-emitting elements 2 a arearrayed in a predetermined pattern, such as a matrix for example.

The driving section 3 includes an electrical circuit for driving theemission section 2.

The power supply circuit 4 generates a power supply voltage for thedriving section 3 (a driving voltage Vd described later) on the basis ofan input voltage (an input voltage Vin described later) from a sourcesuch as a battery not illustrated that is provided in the distancemeasuring apparatus 1, for example. The driving section 3 drives theemission section 2 on the basis of the power supply voltage.

Light emitted by the emission section 2 illuminates, through theemission-side optical system 5, a subject S treated as the target ofdistance measurement. Thereafter, reflected light from the subject S outof the light emitted in this way is incident on the imaging surface ofthe image sensor 7 through the imaging-side optical system 6.

The image sensor 7 is an image sensor such as a charge-coupled device(CCD) sensor or a complementary metal-oxide semiconductor (CMOS) sensorfor example that receives reflected light from the subject S incidentthrough the imaging-side optical system 6 as above, and converts thereceived light to output an electrical signal.

The image sensor 7 executes processes such as a correlated doublesampling (CDS) process and an automatic gain control (AGC) process onthe electrical signal obtained by photoelectric conversion of thereceived light, and furthermore performs an analog/digital (A/D)conversion process. An image signal is then output as digital data tothe image processing section 8 downstream.

Additionally, the image sensor 7 in this example outputs a framesynchronization signal Fs to the driving section 3. With thisarrangement, the driving section 3 is capable of causing thelight-emitting elements 2 a in the emission section 2 to emit light attimings according to the frame cycle of the image sensor 7.

The image processing section 8 is configured as an image processor suchas a digital signal processor (DSP), for example. The image processingsection 8 performs various types of image signal processing on thedigital signal (image signal) input from the image sensor 7.

The control section 9 is provided with an information processing devicesuch as a microcomputer including components such as a centralprocessing unit (CPU), read-only memory (ROM), and random access memory(RAM), or a DSP. The control section 9 controls the driving section 3for controlling the emission operations by the emission section 2 andcontrols imaging operations by the image sensor 7.

The control section 9 includes functions that act as a distancemeasurement section 9 a. The distance measurement section 9 a measuresthe distance to the subject S on the basis of the image signal inputthrough the image processing section 8 (that is, the image signalobtained by receiving reflected light from the subject S). The distancemeasurement section 9 a in this example measures the distance todifferent portions of the subject S, thereby making it possible toidentify the three-dimensional shape of the subject S.

Herein, specific techniques of measuring distance in the distancemeasuring apparatus 1 will be described in further detail later.

The temperature detection section 10 detects the temperature of theemission section 2. A configuration that detects temperature using adiode for example can be adopted as the temperature detection section10.

In this example, information about the temperature detected by thetemperature detection section 10 is supplied to the driving section 3,thereby enabling the driving section 3 to drive the emission section 2on the basis of the information about the temperature.

2. DISTANCE MEASURING TECHNIQUES

As the technique of measuring distance in the distance measuringapparatus 1, a technique of measuring distance according to a structuredlight (STL) method or a time of flight (ToF) method can be adopted, forexample.

The STL method measures distance on the basis of an image obtained byimaging the subject S illuminated with light having a predeterminedlight/dark pattern, such as a dot pattern or a grid pattern, forexample.

FIG. 2 is a diagram explaining the STL method.

In the STL method, the subject S is illuminated with pattern light Lphaving a dot pattern like the one illustrated in FIG. 2A, for example.The pattern light Lp is divided into a plurality of blocks BL, and adifferent dot pattern is assigned to each block BL (the dot patterns arenot duplicated among the blocks BL).

FIG. 2B is a diagram explaining the principle of distance measurementaccording to the STL method.

In the example herein, a wall W and a box BX placed in front are treatedas the subject S, and the subject S is illuminated with pattern lightLp. In the diagram, “G” schematically represents the angle of view ofthe image sensor 7.

Also, “BLn” in the diagram means the light from a certain block BL amongthe pattern light Lp, and “dn” means the dot pattern of the block BLnappearing in the captured image obtained by the image sensor 7.

Here, in the case where the box BX in front of the wall W does notexist, the dot pattern of the block BLn appears in the captured image ata position “dn′” in the diagram. In other words, the position where thepattern of the block BLn appears in the captured image is differentbetween the case where the box BX exists and the case where the box BXdoes not exist, and more specifically, a distortion in the patternoccurs.

The STL method is a method of obtaining the shape and the depth of thesubject S by utilizing how the illuminating pattern is distorted by thephysical shape of the subject S in this way. Specifically, the STLmethod is a method of obtaining the shape and the depth of the subject Sfrom the way in which the pattern is distorted.

In the case of adopting the STL method, an infrared (IR) image sensorwith a global shutter is used as the image sensor 7, for example.Additionally, in the case of the STL method, the distance measurementsection 9 a controls the driving section 3 such that the emissionsection 2 emits pattern light, and in addition, detects patterndistortion in the image signal obtained through the image processingsection 8, and calculates the distance on the basis of the way in whichthe pattern is distorted.

Next, the ToF method measures the distance to a target by detecting thetime of flight (time difference) of light that is emitted by theemission section 2, reflected by the target, and arrives at the imagesensor 7.

In the case of adopting what is called the direct ToF method as the ToFmethod, a single-photon avalanche diode (SPAD) is used as the imagesensor 7, and the emission section 2 is pulse-driven. In this case, thedistance measurement section 9 a calculates the time difference fromemission to reception for light that is emitted by the emission section2 and received by the image sensor 7 on the basis of the image signalinput through the image processing section 8, and calculates thedistance to different portions of the subject S on the basis of the timedifference and the speed of light.

Note that in the case of adopting what is called the indirect ToF method(phase difference method) as the ToF method, an IR image sensor is usedas the image sensor 7, for example.

3. CIRCUIT CONFIGURATION RELATED TO EMISSION DRIVING

FIG. 3 illustrates an exemplary circuit configuration of a light sourceapparatus 100 that includes the emission section 2, the driving section3, and the power supply circuit 4 illustrated in FIG. 1. Note that inaddition to the exemplary circuit configuration of the light sourceapparatus 100, FIG. 3 also illustrates the image sensor 7 and thecontrol section 9 illustrated in FIG. 1.

In this example, the emission section 2, the driving section 3, and thepower supply circuit 4 are formed on a common substrate (a substrate Bdescribed later). Here, the configuration unit that includes at leastthe emission section 2 and is formed on a common substrate with theemission section 2 is referred to as the light source apparatus 100.

As illustrated in the diagram, the light source apparatus 100 isprovided with the temperature detection section 10 in addition to theemission section 2, the driving section 3, and the power supply circuit4.

The emission section 2 is provided with a plurality of VCSELlight-emitting elements 2 a as described earlier. In FIG. 3, the numberof light-emitting elements 2 a is treated as “4” for convenience, butthe number of light-emitting elements 2 a in the emission section 2 isnot limited thereto, and is sufficiently at least two or more.

The power supply circuit 4 is provided with a DC/DC converter 40, andgenerates a driving voltage Vd (DC voltage) that the driving section 3uses to drive the emission section 2 on the basis of an input voltageVin supplied as a DC voltage.

The driving section 3 is provided with a driving circuit 30 and adriving control section 31.

The driving circuit 30 includes a driving transistor Q1 and a switch SWfor each light-emitting element 2 a, as well as a transistor Q2 and aconstant current source 30 a.

A field-effect transistor (FET) is used for the driving transistor Q1and the transistor Q2, and in this example, a P-channelmetal-oxide-semiconductor (MOS) FET, or MOSFET, is used.

The driving transistors Q1 are connected in a parallel relationship withrespect to the output line of the DC/DC converter 40, or in other wordsthe supply line of the driving voltage Vd, and the transistor Q2 isconnected in parallel with the driving transistors Q1.

Specifically, the source of each of the driving transistors Q1 and thetransistor Q2 is connected to the output line of the DC/DC converter 40.The drain of each driving transistor Q1 is connected to the anode of acorresponding light-emitting element 2 a among the light-emittingelements 2 a in the emission section 2.

As illustrated in the diagram, the cathode of each light-emittingelement 2 a is connected to ground (GND).

The drain of the transistor Q2 is connected to ground through theconstant current source 30 a, while the gate is connected to the nodebetween the drain and the constant current source 30 a.

The gate of each driving transistor Q1 is connected to the gate of thetransistor Q2 through a corresponding switch SW.

In the driving circuit 30 having the above configuration, the drivingtransistors Q1 whose switch SW is ON are electrically conductive, thedriving voltage Vd is applied to the light-emitting elements 2 aconnected to the electrically conductive driving transistors Q1, and thelight-emitting elements 2 a emit light.

At this time, a driving current Id flows to the light-emitting elements2 a, but in the driving circuit 30 having the above configuration, thedriving transistors Q1 and the transistor Q2 form a current mirrorcircuit, and the current value of the driving current Id is set to avalue corresponding to the current value of the constant current source30 a.

By controlling the ON/OFF state of the switches SW in the drivingcircuit 30, the driving control section 31 controls the ON/OFF state ofthe light-emitting elements 2 a.

The frame synchronization signal Fs is supplied to the driving controlsection 31 by the image sensor 7, thereby enabling the driving controlsection 31 to synchronize the ON timings and OFF timings of thelight-emitting elements 2 a with the frame cycle of the image sensor 7.

Additionally, the driving control section 31 is capable of controllingthe ON/OFF state of the light-emitting elements 2 a on the basis of aninstruction from the control section 9.

Additionally, the driving control section 31 in this example controlsthe ON/OFF state of the light-emitting elements 2 a on the basis of thetemperature of the emission section 2 detected by the temperaturedetection section 10.

Here, FIG. 3 illustrates an example of a configuration in which thedriving transistors Q1 are provided on the anode side of thelight-emitting elements 2 a, but like the driving circuit 30Aillustrated in FIG. 4, a configuration in which the driving transistorsQ1 are provided on the cathode side of the light-emitting elements 2 ais also possible.

In this case, the anode of each light-emitting element 2 a in theemission section 2 is connected to the output line of the DC/DCconverter 40.

For each of the driving transistors Q1 and the transistor Q2 forming acurrent mirror circuit, an N-channel MOSFET is used. The drain and thegate of the transistor Q2 is connected to the output line of the DC/DCconverter 40 through the constant current source 30 a, while the sourceis connected to ground.

The drain of each driving transistor Q1 is connected to the cathode ofthe corresponding light-emitting element 2 a, while the source isconnected to ground. The gate of each driving transistor Q1 is connectedto the gate and the drain of the transistor Q2 through eachcorresponding switch SW.

In this case as well, by controlling the ON/OFF state of the switchesSW, the driving control section 31 can turn the light-emitting elements2 a ON/OFF.

FIG. 5 illustrates an exemplary configuration of a light sourceapparatus 100A as a modification.

The light source apparatus 100A is provided with a power supply circuit4A instead of the power supply circuit 4 and a driving section 3Ainstead of the driving section 3.

The power supply circuit 4A includes multiple (in the illustratedexample, two) DC/DC converters 40. An input voltage Vin1 is supplied toDC/DC converter 40, while an input voltage Vin2 is supplied to the otherDC/DC converter 40. The driving section 3A is provided with multipledriving circuits 30 that accept the input of the driving voltage Vd fromthe respectively different DC/DC converters 40. As illustrated in thediagram, in each driving circuit 30, a variable current source 30 b isprovided instead of the constant current source 30 a. The variablecurrent source 30 b is a current source having a variable current value.

In this case, the light-emitting elements 2 a in the emission section 2are divided into multiple light-emitting element groups whose states arecontrolled ON/OFF by different driving circuits 30.

The driving control section 31 in this case controls the ON/OFF state ofthe switches SW in each driving circuit 30.

Like the light source apparatus 100A, by taking a configuration in whichat least the pair of the DC/DC converter 40 and the driving circuit 30are reproduced as multiple subsystems, the driving current Id of thelight-emitting elements 2 a can be set to a different value for eachsubsystem. For example, by causing the voltage value of the drivingvoltage Vd and the current value of the variable current source 30 b tobe different for each subsystem, the value of the driving current Id canbe made different for each subsystem. Also, in a configuration in whichthe DC/DC converter 40 keeps the driving current Id constant, by makingthe target value of the constant current control different for eachDC/DC converter 40, the value of the driving current Id can be madedifference for each subsystem.

In the case of adopting a configuration like FIG. 5, it is conceivableto make the values of the driving voltage Vd and the driving current Iddifferent for each subsystem according to factors such as the emissionintensity distribution and the temperature distribution in the emissionsection 2. For example, it is conceivable to take measures such asincreasing the driving current Id and also raising the driving voltageVd for a subsystem corresponding to a high-temperature location in theemission section 2.

4. VARIATIONS IN SUBSTRATE CONFIGURATION

Here, the light source apparatus 100 may take the configurationsillustrated in FIGS. 6 to 8.

As illustrated in FIG. 6A, the light source apparatus 100 may take aconfiguration in which a chip Ch2 containing a circuit that acts as theemission section 2, a chip Ch3 containing a circuit that acts as thedriving section 3, and a chip Ch4 containing the power supply circuit 4are formed on the same substrate B.

Additionally, the driving section 3 and the power supply circuit 4 mayalso be formed in the same chip Ch34, and in this case, the light sourceapparatus 100 may take a configuration in which the chip Ch2 and thechip Ch34 are formed on the same substrate B, as illustrated in FIG. 6B.

It is also possible to take a configuration in which a chip Ch ismounted on another chip Ch.

In this case, the light source apparatus 100 may take a configuration inwhich the chip Ch3 having the chip Ch2 mounted thereon and the chip Ch4are formed on the substrate B like in FIG. 7A, a configuration in whichthe chip Ch3 having the chip Ch2 and the chip Ch4 mounted thereon isformed on the substrate B like in FIG. 7B, or a configuration in whichthe chip Ch34 having the chip Ch2 mounted thereon is formed on thesubstrate B like in FIG. 7C, for example.

Additionally, the light source apparatus 100 may also take aconfiguration that includes the image sensor 7.

For example, FIG. 8A illustrates an example of a configuration of thelight source apparatus 100 in which the chip Ch2, the chip Ch3, and thechip Ch4 as well as a chip Ch7 containing a circuit that acts as theimage sensor 7 are formed on the same substrate B.

Also, FIG. 8B illustrates an example of a configuration of the lightsource apparatus 100 in which the chip Ch34 having the chip Ch2 mountedthereon and the chip Ch7 are formed on the same substrate B.

Note that the light source apparatus 100A described above likewise mayadopt a configuration similar to those described using FIGS. 6 to 8.

Here, regarding the temperature detection section 10, in the case wherethe chip Ch2 is formed on the substrate B like in FIGS. 6A, 6B, and 8Afor example, it is sufficient to form temperature detection elementssuch as diodes at positions near the chip Ch2 in the substrate B (suchas positions beside the chip Ch2 on the substrate B, for example).

Also, in the case where the chip Ch2 is mounted onto another chip Chlike in FIGS. 7A to 7C and FIG. 8B, it is sufficient to form thetemperature detection elements at positions near the chip Ch2 in theother chip Ch (such as positions underneath of the chip Ch2, forexample).

The temperature detection section 10 may include a plurality oftemperature sensors 10 a including temperature detection elements suchas diodes.

FIG. 9 illustrates an exemplary arrangement of the temperature sensors10 a in the case where the temperature detection section 10 includes aplurality of temperature sensors 10 a.

In the example of FIG. 9, the plurality of temperature sensors 10 a arenot concentrated in a single location, but are dispersed in a planeparallel to the plane in which the light-emitting elements 2 a arearrayed. Specifically, the plurality of temperature sensors 10 a may bearranged such that one temperature sensor 10 a is disposed for eachemission block containing a predetermined number of light-emittingelements 2 a, such as a 2×2 block containing a total of fourlight-emitting elements 2 a, for example. In this case, the temperaturesensors 10 a may be arranged at equal intervals in a plane parallel tothe plane in which the light-emitting elements 2 a are arrayed.

Note that although FIG. 9 illustrates an example of arranging fourtemperature sensors 10 a with respect to nine light-emitting elements 2a, but the number of disposed light-emitting elements 2 a and the numberof disposed temperature sensors 10 a are not limited thereto.

Also, by dispersing the plurality of temperature sensors 10 a like inthe examples of FIG. 9, it is possible to detect an in-plane temperaturedistribution of the emission section 2. In addition, differenttemperatures can be detected for different areas of the emissionsurface, and furthermore, by increasing the number of disposedtemperature sensors 10 a, it is also possible to detect differenttemperatures for each of the light-emitting elements 2 a.

5. EXEMPLARY VCSEL STRUCTURE

Next, an exemplary structure of the chip Ch2 in which the emissionsection 2 is formed will be described with reference to FIGS. 10 and 11.

FIG. 10 illustrates an exemplary structure of the chip Ch2 in the caseof being formed on the substrate B like in FIGS. 6A, 6B, and 8A, whileFIG. 11 illustrates an exemplary structure of the chip Ch2 in the caseof being mounted onto another chip Ch like in FIGS. 7A to 7C and FIG.8B.

Note that, as an example, FIGS. 10 and 11 illustrate an exemplarystructure corresponding to the case where the driving circuit 30 isinserted on the anode side of the light-emitting elements 2 a (see FIG.3).

As illustrated in FIG. 10, in the chip Ch2, the portions correspondingto each of the light-emitting elements 2 a are formed as mesas M.

A semiconductor substrate 20 is used as the substrate of the chip Ch2,and a cathode electrode Tc is formed on the underside of thesemiconductor substrate 20. For the semiconductor substrate 20, agallium arsenide (GaAs) substrate is used, for example.

On the semiconductor substrate 20, in each mesa M, a first multilayerreflective layer 21, an active layer 22, a second multilayer reflectivelayer 25, a contact layer 26, and an anode electrode Ta are formed inorder from bottom to top.

A current constriction layer 24 is formed in a part (specifically thelower part) of the second multilayer reflective layer 25. Also, theportion including the active layer 22 that is sandwiched between thefirst multilayer reflective layer 21 and the second multilayerreflective layer 25 acts as a resonator 23.

The first multilayer reflective layer 21 is formed using a compoundsemiconductor exhibiting N-type conductivity, while the secondmultilayer reflective layer 25 is formed using a compound semiconductorexhibiting P-type conductivity.

The active layer 22 acts as a layer for generating laser light, whilethe current constriction layer 24 acts as a layer that injects currentefficiently into the active layer 22 and achieves a lens effect.

After the mesas M are formed, the current constriction layer 24 issubjected to selective oxidation in the unoxidized state, and includes acentral oxidized region (also referred to as a selectively oxidizedregion) 24 a and an unoxidized region 24 b that is not oxidized in theperiphery of the oxidized region 24 a. In the current constriction layer24, a current constricting structure is formed by the oxidized region 24a and the unoxidized region 24 b, and current is conducted to thecurrent constriction region as the unoxidized region 24 b.

The contact layer 26 is provided to ensure an ohmic contact with theanode electrode Ta.

The anode electrode Ta is formed on the contact layer 26 in an annular(ring) shape or the like that is open in the center for example whenlooking at a plan view of the substrate B. In the contact layer 26, theportion where the anode electrode Ta is not formed on top acts as anopening 26 a.

Light generated in the active layer 22 travels back and forth inside theresonator 23 and then is emitted to the outside through the opening 26a.

Here, the cathode electrode Tc in the chip Ch2 is connected to groundthrough a ground lead Lg formed in a wiring layer of the substrate B.

Also, in the diagram, a pad Pa represents a pad for the anode electrodeformed on the substrate B. The pad Pa is connected to the drain of anyone of the driving transistors Q1 included in the driving circuit 30through a lead Ld formed in the wiring layer of the substrate B.

In the diagram, the anode electrode Ta is illustrated as being connectedto the single pad Pa through an anode lead La formed on the chip Ch2 anda bonding wire BW for only one light-emitting element 2 a, but the padPa and the lead Ld are formed for each light-emitting element 2 a on thesubstrate B, and furthermore, the anode lead La is formed for each ofthe light-emitting elements 2 a on the chip Ch2, and the anodeelectrodes Ta of the individual light-emitting elements 2 a areconnected to the corresponding pad Pa through the corresponding anodelead La and bonding wire BW.

Next, in the case of FIG. 11, a back-illumination chip Ch2 is used asthe chip Ch2. In other words, rather than emitting light in the upwarddirection (surface direction) of the semiconductor substrate 20 like theexample in FIG. 10, a chip Ch2 of a type that emits light in the backdirection of the semiconductor substrate 20.

In this case, an opening for emitting light is not formed in the anodeelectrode Ta, and the opening 26 a is not formed in the contact layer26.

In the chip Ch3 (or the chip Ch34; the same applies hereinafter in thedescription of FIG. 11) in which the driving section 3 (driving circuit30) is formed, the pad Pa for establishing an electrical connection withthe anode electrode Ta is formed for each light-emitting element 2 a. Inthe wiring layer of the chip Ch3, the lead Ld is formed for each pad Pa.Although omitted from illustration, each of the pads Pa is connected, bythese leads Ld, to the drain of a corresponding driving transistor Q1 inthe driving circuit 30 formed in the chip Ch3.

Also, in the chip Ch2, the cathode electrode Tc is connected to anelectrode Tc1 and an electrode Tc2 via leads Lc1 and Lc2, respectively.The electrode Tc1 and the electrode Tc2 are electrodes for respectivelyconnecting with a pad Pc1 and a pad Pc2 formed in the chip Ch3.

In the wiring layer of the chip Ch3, a ground lead Lg1 connected to thepad Pc1 and a ground lead Lg2 connected to the pad Pc2 are formed.Although not illustrated, these ground leads Lg1 and Lg2 are connectedto ground.

The connections between each anode electrode Ta in the chip Ch2 and eachpad Pa in the chip Ch3 as well as the connections between the electrodesTc1 and Tc2 in the chip Ch2 and the pads Pc1 and Pc2 in the chip Ch3 areestablished through respective solder bumps Hb.

In other words, the mounting of the chip Ch2 on the chip Ch3 in thiscase is achieved by what is called flip chip mounting.

6. Arrangement Relationship Between Light-Emitting Elements and DrivingTransistors

Next, FIGS. 12 to 15 will be used to describe the arrangementrelationship between the emission section 2 and the driving circuit 30in the case where the chip Ch2 is mounted onto the chip Ch3 (or the chipCh34; the same applies to the description hereinafter) as illustrated inFIGS. 7A to 7C and FIG. 8B in the light source apparatus 100.

In the present embodiment, a back-illumination chip Ch2 like the oneillustrated in FIG. 11 is used as an example. In this example, astructure corresponding to the case where the driving circuit 30 isinserted on the anode side of the light-emitting elements 2 a asillustrated in FIG. 3 is adopted.

Note that the chip Ch2 is not limited to the back-illumination type, anda structure like the one illustrated in FIG. 10 may also be adopted.Additionally, it is also possible to take a configuration in which thedriving transistors Q1 are provided on the cathode side of thelight-emitting elements 2 a, like the driving circuit 30A illustrated inFIG. 4.

In the driving circuit 30 of the driving section 3 in FIG. 3, thedriving transistors Q1 whose switch SW is ON are electricallyconductive, the driving voltage Vd is applied to the light-emittingelements 2 a of the emission section 2 connected to the electricallyconductive driving transistors Q1, and the light-emitting elements 2 aemit light.

When measuring distance by causing the emission section 2 in which aplurality of VCSEL light-emitting elements 2 a is arrayed to emit lightlike the distance measuring apparatus 1 described above, the pluralityof light-emitting elements 2 a is made to emit light simultaneously orby time division.

When executing such light emission, the driving transistors Q1 in thedriving circuit 30 of the chip Ch3 generate heat, which causes thetemperature of the chip Ch2 in which the light-emitting elements 2 a areformed to rise easily, and depending on the ambient temperature, thismay lead to a heat-induced malfunction such as a drop in the emissionefficiency of the light-emitting elements 2 a.

Also, the temperature of the light-emitting elements 2 a rises due toemission, and generated heat may lead to degraded circuitcharacteristics in the driving circuit 30 that drives the light-emittingelements 2 a.

Accordingly, FIG. 12 will be used to describe the arrangementrelationship between the emission section 2 (chip Ch2) and the drivingsection 3 (chip Ch3) for avoiding interference due to mutual heat. FIG.12A is a diagram schematically illustrating the arrangement relationshipbetween the chip Ch2 and the chip Ch3 provided on the substrate B, andFIG. 12B is a diagram schematically illustrating a cross section of theinternal structure of the chip Ch3 with the chip Ch2 mounted thereon.

As illustrated in FIG. 12A, in the state in which the chip Ch2 ismounted onto the chip Ch3, three regions (hereinafter also referred toas driving transistor placement regions ar) containing the drivingtransistors Q1 for causing each light-emitting element 2 a to emit lightare provided in the chip Ch3. As illustrated in FIG. 12B, the pluralityof driving transistors Q1 is provided in the driving circuit 30 in eachof the driving transistor placement regions ar. In this diagram, all ofthe driving transistor placement regions ar are provided at positionsoverlapping the planar face of the chip Ch2.

Note that although an example of providing three driving transistorplacement regions ar is described as an example herein for convenienceof illustration, the driving transistor placement regions ar are notlimited to three, and it is possible to provide a one or a plurality ofdriving transistor placement regions ar (the same applies to thedescription hereinafter).

In such a configuration, in a case where the plurality of light-emittingelements 2 a are made to emit light simultaneously or by time division,the corresponding driving transistor placement regions ar generate heat.Consequently, the temperature of the chip Ch2 contacting the drivingtransistor placement regions ar rises in association with thisgeneration of heat.

Additionally, heat is generated by the simultaneous or time-divisionemission of light by the plurality of light-emitting elements 2 aprovided in the emission section 2, and this heat causes the temperatureof the driving circuits 30 contained in the driving transistor placementregions ar to rise.

Accordingly, in the present embodiment, the driving transistor placementregions ar are disposed at positions that do not overlap with the chipCh2 containing the light-emitting elements 2 a.

FIG. 13 illustrates an example of the arrangement. FIG. 13A is a diagramschematically illustrating the arrangement relationship between the chipCh2 and the chip Ch3, and FIG. 13B is a diagram schematicallyillustrating a cross section of the internal structure of the chip Ch3with the chip Ch2 mounted thereon.

As illustrated in FIGS. 13A and 13B, two driving transistor placementregions ar are provided in the chip Ch3, and the driving transistorplacement regions ar are disposed facing each other with the chip Ch2 inbetween. At this time, the driving transistor placement regions ar aredisposed so as not to overlap with the planar face of the chip Ch2(emission section 2).

In this way, by disposing the driving transistor placement regions ar atpositions not below the underside of the chip Ch2, the distance betweenthe driving transistors Q1 of the driving transistor placement regionsar and the chip Ch2 is increased, and the influence on the emissionsection 2 caused by the heat generated by the driving transistors Q1 canbe reduced. Furthermore, the influence on the driving circuit 30 of thedriving transistor placement regions ar caused by the heat generatedwhen the light-emitting elements 2 a provided in the emission section 2emit light can be reduced.

In this way, because the influence of heat can be reduced by disposingthe driving transistor placement regions ar at positions distanced fromthe light-emitting elements 2 a of the emission section 2 that generateheat, it is also possible for a portion of the emission section 2 (chipCh2) to be mounted onto the driving section 3 (chip Ch3) so as tooverlap the driving transistor placement regions ar, insofar as thelight-emitting elements 2 a are arranged so as not to overlap with thedriving transistor placement regions ar.

Similarly, because the influence of heat can be reduced by disposing theemission section 2 at a position distanced from the driving transistorsQ1 of the driving transistor placement regions ar that generate heat, itis also possible for the emission section 2 (chip Ch2) to be mountedonto the driving section 3 (chip Ch3) so as to overlap a portion of thedriving transistor placement regions ar, insofar as the drivingtransistors Q1 are arranged so as not to overlap with the emissionsection 2.

Furthermore, to keep the heat from being concentrated in a singlelocation, when mounting the emission section 2 (chip Ch2) onto thedriving section 3 (chip Ch3), it is desirable to arrange thelight-emitting elements 2 a and the driving transistors Q1 so as not tooverlap each other.

Also, by disposing the disposed driving transistor placement regions arin a plurally dispersed manner, such as by disposing the drivingtransistor placement regions ar at positions facing each other with thechip Ch2 in between like in FIG. 13A, the heat dissipation of eachdriving transistor placement region ar is improved, and a temperaturerise in the driving transistors Q1 can be moderated. With thisarrangement, the influence on the chip Ch2 caused by the heat generatedby the driving transistors Q1 can be reduced.

Note that the positions of the driving transistor placement regions arin the chip Ch3 are not limited to the above, and a variety of modes areconceivable. FIG. 14 illustrates examples of arrangements of the drivingtransistor placement regions ar in the chip Ch3.

For example, as illustrated in FIG. 14A, the driving transistorplacement regions ar may be disposed in a single combined region in thechip Ch3 at a position that does not overlap with the chip Ch2.

Also, as illustrated in FIG. 14B, the driving transistor placementregions ar may be disposed along a first edge of the chip Ch2 and alsoalong an edge adjacent to the first edge.

Furthermore, as illustrated in FIG. 14C, it is also conceivable todispose the driving transistor placement regions ar to surround the chipCh2.

Also, the driving transistors Q1 in all of the driving transistorplacement regions ar do not necessarily need to be provided so as not tooverlap with the chip Ch2. In other words, as long as the temperaturerise in the chip Ch2 does not exceed a value that would cause amalfunction, the driving transistor placement regions ar may also beprovided so as to overlap with the chip Ch2.

As illustrated in FIGS. 15A and 15B for example, in the case where threedriving transistor placement regions ar are provided in the chip Ch3,two of the driving transistor placement regions ar may be provided atpositions facing each other with the chip Ch2 in between, while theremaining single driving transistor placement region ar may be providedso as to overlap with the chip Ch2 (emission section 2). In this case,some of the driving transistors Q1 are disposed at positions overlappingthe chip Ch2.

7. Leads that Connect Light-Emitting Elements and Driving Transistors

Next, the structure of the leads Lt that electrically connect thelight-emitting elements 2 a and the driving transistors Q1 will bedescribed using FIGS. 16 and 17. For the leads Lt, metal leads such asCu leads are used, for example.

If the wiring resistance value of the leads Lt rises, the rising time ofthe signal pulses increases, which may cause phenomena such as anincrease in power consumption due to ohmic loss and a rise intemperature associated therewith. Consequently, it is desirable to formthe leads so as to moderate increases in the wiring resistance of theleads Lt.

FIG. 16 is a diagram schematically illustrating a cross section of thechip Ch3 with the chip Ch2 mounted thereon.

As illustrated in FIG. 16A, the chip Ch3 is formed in a multilayerstructure, and includes a plurality of wiring layers Ly1, Ly2, Ly3, andso on. The chip Ch3 may also be configured as a single-layer structure,but a multilayer structure is desirable. Note that in the following,components such as insulating layers will be omitted from illustrationto avoid confusion, and the driving transistors Q1 will be illustratedschematically.

The reason why the chip Ch3 has a multilayer structure is that theemission section 2 is provided with hundreds of light-emitting elements2 a, and if one attempts to provide the leads Lt for connecting thesethe light-emitting elements 2 a to the driving transistors Q1 in asingle-layer structure, the wiring cross-sectional area SA (hereinafteralso simply referred to as the cross-sectional area SA) per lead Ltwould become very small, making it difficult to secure enough area tomoderate an increase in the wiring resistance of each lead Lt.

Here, the wiring cross-sectional area refers to the cross-sectional areawhen taking a cross section in a plane perpendicular to the extensiondirection of the lead. The extension direction means to the direction inwhich a lead Lt runs from a driving transistor Q1 to a light-emittingelement 2 a, and refers to the longitudinal direction of the lead Lt forexample.

Although not illustrated, the chip Ch3 according to the presentembodiment has seven wiring layers Ly.

In the driving transistor placement regions ar of the chip Ch3, thedriving transistors Q1 are provided in each of the wiring layers Ly, andthe drain of each driving transistor Q1 is connected to the anode of acorresponding light-emitting element 2 a among the light-emittingelements 2 a in the emission section 2 through a lead Lt.

A driving transistor Q1 provided in the uppermost wiring layer Ly1 isconnected to a predetermined light-emitting element 2 a positioned nearthe periphery of the chip Ch2 (that is, a light-emitting element 2 a ashort distance away from the driving transistor Q1) through a lead Lt1.

Also, a driving transistor Q1 provided in the wiring layer Ly2 below thewiring layer Ly1 is connected, through a lead Lt2, to a predeterminedlight-emitting element 2 a positioned farther inward than thelight-emitting element 2 a connected in the wiring layer Ly1.

Further, a driving transistor Q1 provided in the wiring layer Ly3 belowthe wiring layer Ly2 is connected, through a lead Lt3, to apredetermined light-emitting element 2 a positioned farther inward thanthe light-emitting element 2 a connected in the wiring layer Ly2.

Consequently, as the wiring layers Ly proceed to lower layers, thedistance from the driving transistors Q1 to the light-emitting elements2 a increases, and the length of the leads Lt connecting the drivingtransistors Q1 and the light-emitting elements 2 a also increasescorrespondingly. Specifically, when comparing the lead Lt1 provided inthe wiring layer Ly1, the lead Lt2 provided in the wiring layer Ly2, andthe lead Lt3 provided in the wiring layer Ly3, the lead Lt2 is longerthan the lead Lt1 and the lead Lt3 is longer than the lead Lt2.

In this way, by connecting the driving transistors Q1 in higher layersto light-emitting elements 2 a a shorter distance away, a layout inwhich the leads Lt do not intersect each other is achieved easily.Consequently, it is possible to keep the wiring length from becominglonger than necessary to avoid intersections between the leads Lt, andas a result, an increase in the wiring resistance of the leads Lt can bemoderated.

Also, as the lengths of the leads Lt increase in successively lowerlayers, the wiring resistance of the leads Lt connecting thelight-emitting elements 2 a and the driving transistors Q1 increases.Consequently, there are concerns about the occurrence of phenomena suchas an increase in power consumption for causing the light-emittingelements 2 a to emit light, and a rise in temperature associatedtherewith.

Accordingly, in the present embodiment, the wiring cross-sectional areaSA of the leads Lt is enlarged according to the wiring length, and byenlarging the wiring cross-sectional area SA, an increase in the wiringresistance of the leads Lt is moderated. In FIG. 16A, cross-sectionalareas SA1 to SA6 are illustrated for the leads Lt1 to Lt3 at anypositions.

For example, in the lead Lt2, the wiring cross-sectional area SA changesfrom SA2 to SA3 as the wiring length becomes longer.

At this time, by causing the cross-sectional area SA3 to have a greaterwiring width in the vertical direction (thickness direction) of thewiring layers Ly compared to the cross-sectional area SA2, thecross-sectional area SA3 is formed having a larger wiringcross-sectional area than the cross-sectional area SA2.

Similarly, the wiring cross-sectional area SA of the lead Lt3 changesfrom SA4 to SA5 and SA6 according to the wiring length, and bysuccessively increasing the wiring width in the vertical direction(thickness direction) of the wiring layers Ly, the lead Lt3 is formedhaving a larger wiring cross-sectional area.

In addition, the wiring length increases further for the leads Ltprovided in the lower wiring layers Ly as described above, and as aresult, the leads Lt are formed having larger wiring cross-sectionalareas SA. For example, the largest cross-sectional area SA6 of the leadLt3 provided in the lower wiring layer Ly3 is larger than the largestcross-sectional area SA3 of the lead Lt2 provided in the wiring layerLy2.

At this time, to enlarge the wiring cross-sectional area SA of the leadsLt, it is also conceivable to provide the leads Lt spanning a pluralityof wiring layers. For example, when enlarging the lead Lt2 provided inthe wiring layer Ly2 illustrated in FIG. 16A from the cross-sectionalarea SA2 to the cross-sectional area SA3, the surplus region in thewiring layer Ly1 can be used. In other words, by forming the lead Lt2 soas to span the wiring layer Ly2 and the wiring layer Ly1, thecross-sectional area SA3 can be enlarged more than the cross-sectionalarea SA2.

Similarly, when enlarging the lead Lt3 provided in the wiring layer Ly3from the cross-sectional area SA4 to the cross-sectional area SA5, thesurplus region in the wiring layer Ly2 can be used in addition to thewiring layer Ly3. Also, when enlarging the lead Lt3 formed spanning thewiring layer Ly3 and the wiring layer Ly2 from the cross-sectional areaSA5 to the cross-sectional area SA6, the surplus region in the wiringlayer Ly1 can be used in addition to the wiring layer Ly3 and the wiringlayer Ly2 to form the leads Lt.

In this way, by utilizing the surplus regions of the wiring layers Ly toenlarge the wiring cross-sectional area SA, an increase in the wiringresistance of the leads Lt can be moderated.

Note that, as illustrated in FIG. 16B for example, the lead Lt3 that hadbeen provided in the lower wiring layer Ly3 may also be disposed in thewiring layer Ly1 along the way.

FIG. 17 is a diagram schematically illustrating the chip Ch3 with thechip Ch2 mounted thereon. As described above, in the driving transistorplacement regions ar of the chip Ch3, the driving transistors Q1 areprovided, and the drain of each driving transistor Q1 is connected tothe anode of a corresponding light-emitting element 2 a among thelight-emitting elements 2 a in the emission section 2 through a lead Lt.

Note that although the chip Ch3 is formed having a multilayer structurein actuality, among the plurality of wiring layers Ly, only the wiringlayer Ly1 is illustrated in the diagram to avoid confusion. Likewise,regarding the light-emitting elements 2 a, although the emission section2 actually includes a plurality of light-emitting elements 2 a, onlythree light-emitting elements 2 a are illustrated here as an example.

First, in the wiring layer Ly1, a predetermined driving transistor Q1 isconnected to a predetermined light-emitting element 2 a positioned nearthe periphery of the chip Ch2 (that is, a light-emitting element 2 a ashort distance away from the driving transistor Q1) through a lead Lt4.

Additionally, the next driving transistor Q1 provided in the same wiringlayer Ly1 is connected, through a lead Lt5, to a predeterminedlight-emitting element 2 a positioned farther inward than thelight-emitting element 2 a connected by the lead Lt4.

Furthermore, the next driving transistor Q1 provided in the same wiringlayer Ly1 is connected, through a lead Lt6, to a predeterminedlight-emitting element 2 a positioned farther inward than thelight-emitting element 2 a connected by the lead Lt5.

Consequently, when successively connecting the driving transistors Q1 tothe light-emitting elements 2 a through the leads Lt, the distance fromthe driving transistors Q1 to the light-emitting elements 2 a graduallyincreases, and therefore the length of the leads Lt connecting thedriving transistors Q1 and the light-emitting elements 2 a graduallyincreases. Specifically, when comparing the lead Lt4, the lead Lt5, andthe lead Lt6, the lead Lt5 is longer than the lead Lt4, and the lead Lt6is longer than the lead Lt5 (and the lead Lt4).

In FIG. 17, cross-sectional areas SA7 to SA11 are illustrated for theleads Lt4 to Lt6 at any positions.

For example, in the lead Lt5, the wiring cross-sectional area SA changesfrom SA8 to SA9 as the wiring length becomes longer.

At this time, by causing the cross-sectional area SA9 to have a greaterwiring width in the direction of the plane (planar direction)perpendicular to the vertical direction (thickness direction) of thewiring layers Ly compared to the cross-sectional area SA8, thecross-sectional area SA9 is formed having a larger wiringcross-sectional area than the cross-sectional area SA8.

Similarly, the wiring cross-sectional area SA of the lead Lt6 changesfrom SA10 to SA11 according to the wiring length, and by successivelyincreasing the wiring width in the planar direction of the wiring layersLy, the lead Lt6 is formed having a larger wiring cross-sectional area.

In this way, as the wiring length becomes longer, the wiringcross-sectional area SA of the leads Lt becomes larger. For example, thelargest cross-sectional area SA11 of the lead Lt6 having a longer wiringlength than the lead Lt5 has a larger wiring cross-sectional area thanthe largest cross-sectional area SA9 of the lead Lt5.

With this arrangement, it is possible to moderate an increase in wiringresistance by increasing the wiring width in the planar direction of thewiring layers Ly.

Note that in the above, the wiring width in the planar direction of thewiring layers Ly and the wiring width in the thickness direction of thewiring layers Ly are described separately, but the wiringcross-sectional area may also be enlarged by increasing both the wiringwidth in the planar direction of the wiring layers Ly and the wiringwidth in the thickness direction of the wiring layers Ly. With thisarrangement, a moderation of the increase in wiring resistance is alsoattained.

Next, an example of the leads Lt that electrically connect thelight-emitting elements 2 a and the driving transistors Q1 will bedescribed using FIG. 18.

First, as illustrated in FIG. 14A, in the case where the drivingtransistor placement region ar in which the driving transistors Q1 aredisposed is provided in a single location with respect to the chip Ch2,the driving transistors Q1 are connected all the way to thelight-emitting elements 2 a provided on the opposite side of the chipCh2 away from the driving transistor placement region ar (refer to thedistance X1 in FIG. 18). For this reason, the wiring resistanceincreases due to the longer leads Lt, and as a result of enlarging thewiring cross-sectional area SA of the leads Lt to moderate the increasein the wiring resistance, more space is needed to provide the leads Lt.

Accordingly, as illustrated in FIGS. 13A and 18, it is conceivable todispose the driving transistor placement regions ar (ar1 and ar2) atpositions facing each other in the chip Ch3 with the chip Ch2 inbetween.

FIG. 18 schematically illustrates a cross section of the chip Ch3 withthe chip Ch2 mounted thereon.

Here, for convenience, an example in which the emission section 2 isprovided with six light-emitting elements 2 a (2 a-1 to 2 a-6) will bedescribed. Each of the provided light-emitting elements 2 a-1 to 2 a-6is not limited to being a single light-emitting element, and each may beformed as a plurality of light-emitting elements 2 a, for example.

In this example, the driving transistor Q1 provided in the uppermostwiring layer Ly1 of the driving transistor placement region ar1 isconnected, through the lead Lt1, to a predetermined light-emittingelement 2 a-1 disposed near the periphery of the chip Ch2 on the sidenear the driving transistor placement region ar1. Additionally, as thewiring layers proceed to the lower layers Ly2, Ly3, and so on, thedriving transistor Q1 are respectively connected, through the leads Lt2,Lt3, and so on, to predetermined light-emitting elements 2 a-2, 2 a-3,and so on farther inward than the light-emitting element 2 a connectedto the lead Lt in a higher layer.

At this point, if the driving transistor placement regions ar areassumed to be provided only in a single location as the drivingtransistor placement region ar1, for example, new driving transistors Q1are provided in wiring layers such as Ly4, Ly5, and Ly6 not illustratedfor example, and are connected to the light-emitting elements 2 a-4, 2a-5, and 2 a-6 by leads Lt4, Lt5, and Lt6 not illustrated. In this case,the length of the lead Lt6 joining the light-emitting element 2 a-6farthest away from the driving transistor placement region an to thecorresponding driving transistor Q1 is a distance X1.

However, in this example, the driving transistor placement region ar2 isprovided in addition to the driving transistor placement region ar1, andlike the driving transistor placement region ar1, the drivingtransistors Q1 are successively connected to the light-emitting element2 a-6 by the wiring layer Lya, the light-emitting element 2 a-5 by thewiring layer Lyb, and the light-emitting element 2 a-4 by the wiringlayer Lyc.

In this case, because the number of light-emitting elements 2 a toconnect to the driving transistors Q1 in each driving transistorplacement region ar is decreased, the length of the lead Lt3 joining thelight-emitting element 2 a-3 farthest away from the driving transistorplacement region an to the corresponding driving transistor Q1 is adistance X2, which is shorter than the distance X1 in the case where thedriving transistor placement regions ar are provided only in a singlelocation. Consequently, the maximum length of the leads Lt to beprovided can be shortened.

With this arrangement, it is possible to moderate an increase in thewiring resistance of the leads Lt. Furthermore, it is possible to keepthe wiring cross-sectional area SA of the leads Lt from becoming largerthan necessary, which is favorable for designing the wiring in thewiring layers Ly.

8. SUMMARY OF EMBODIMENT AND MODIFICATIONS

The light source apparatus (the distance measuring apparatus 1) as anembodiment described above includes an emission section 2 in which aplurality of vertical-cavity surface-emitting laser light-emittingelements 2 a is arrayed, and a driving section 3 configured to cause theplurality of light-emitting elements 2 a to be emitted of the emissionsection 2 to emit light, and at least a portion of a region (the drivingtransistor placement region ar) including driving elements (the drivingtransistor Q1) in the driving section 3 is disposed so as not to overlapwith the emission section 2 (see FIGS. 7, 8B, 13, and the like).

With this arrangement, the heat generated from the driving transistorsQ1 and transmitted to the light-emitting elements 2 a is reduced. Also,the heat generated by the light-emitting elements 2 a and transmitted tothe driving circuit 30 of the driving section 3 is also reduced.

Consequently, it is possible to prevent a heat-induced malfunction thatoccurs in situations such as when the temperature of the chip Ch2(emission section 2) in which the light-emitting elements 2 a are formedrises easily due to the heat generated by components such as the drivingcircuit 30 (30A) for causing the light-emitting elements 2 a to emitlight, leading to a drop in the emission efficiency of thelight-emitting elements 2 a.

Additionally, it is also possible to prevent a malfunction such asdegraded circuit characteristics in the driving circuit (30A) thatdrives the light-emitting elements 2 a because of heat generated bylight emission from the light-emitting elements 2 a.

Also, in the light source apparatus (distance measuring apparatus 1) asan embodiment, the chip Ch2 in which the emission section 2 is formed ismounted onto the chip Ch3 in which the driving section 3 is formed, andat least a portion of a region (driving transistor placement region ar)including the driving elements (driving transistors Q1) of the drivingsection 3 is disposed so as not to overlap with the light-emittingelements 2 a of the emission section 2 (see FIGS. 13 and 15, forexample).

With this arrangement, the leads Lt that connect the emission section 2and the driving section 3 can be shortened, and an increase in wiringresistance of the leads Lt can be moderated. Also, the drivingtransistor placement regions ar can be provided at a distance from thelight-emitting elements 2 a that generate heat.

Consequently, when causing the light-emitting elements 2 a to emitlight, phenomena such as an increase in power consumption and a rise intemperature associated therewith can be prevented. Also, because theemission section 2 is mounted onto the driving section 3, the distancebetween the light-emitting elements 2 a and the driving transistors Q1is shortened easily. Under such conditions, it is even more importantnot to dispose the driving transistors Q1 overlapping the light-emittingelements 2 a to prevent a heat-induced malfunction.

Furthermore, in the light source apparatus (distance measuring apparatus1) as an embodiment, the driving section 3 includes a plurality ofwiring layers Ly, and leads Lt for electrically connecting the drivingelements (driving transistors Q1) to the light-emitting elements 2 a areformed in the wiring layers Ly (see FIGS. 16A and 18, for example).

With this arrangement, the leads Lt can be arranged while maintainingthe size of the wiring cross-sectional area SA of the leads Lt, and anincrease in the wiring resistance of the leads Lt is moderated.

If one attempts to provide all of the leads Lt for connecting thehundreds of light-emitting elements 2 a provided in the chip Ch2(emission section 2) to the driving transistors Q1 in a single wiringlayer Ly, it would be necessary to reduce the cross-sectional area SAfor each lead Lt, making it difficult to secure enough cross-sectionalarea SA to moderate an increase in the wiring resistance of each leadLt.

Consequently, by adopting the above configuration, of thecross-sectional area SA of each lead Lt can be secured adequately,thereby making it possible to avoid phenomena such as an increase inpower consumption and a rise in temperature associated therewith due tobeing unable to secure a large enough cross-sectional area SA for theleads Lt.

Furthermore, in the light source apparatus (distance measuring apparatus1) as an embodiment, the leads Lt are formed such that the distancebetween the driving elements (driving transistors Q1) and thelight-emitting elements 2 a connected to each other is longer in lowerwiring layers Ly (see FIGS. 16A and 18, for example).

With this arrangement, when drawing out the lead Lt from a lower layertoward a higher layer, it is possible to avoid a situation in which ahigher-layer lead Lt obstructs the drawing-out of the lower-layer leadLt.

Consequently, a shortening of the length of each lead Lt can be attainedwithout complicating the arrangement of the leads Lt. Consequently, anincrease in the wiring resistance of the leads Lt is moderated, andphenomena such as an increase in power consumption and a rise intemperature associated therewith can be prevented.

Also, in the light source apparatus (distance measuring apparatus 1) asan embodiment, a plurality of regions (driving transistor placementregions ar) including the driving elements (driving transistors Q1) areprovided in the driving section 3 (see FIGS. 13, 14, and 18, forexample).

By dividing the driving transistor placement regions ar into a pluralityof regions in this way, the lengths of the leads Lt connecting thedriving transistors Q1 and the light-emitting elements 2 a can beshortened. Consequently, an increase in the wiring resistance of theleads Lt is moderated, and phenomena such as an increase in powerconsumption and a rise in temperature associated therewith can beprevented.

Furthermore, in the light source apparatus (distance measuring apparatus1) as an embodiment, as the lengths of the leads Lt become longer,portions (such as SA3, SA5, and SA6 in FIG. 16, and SA9 and SA11 in FIG.17) of increased cross-sectional area (wiring cross-sectional area SA)when taking a cross section in a plane perpendicular to the extensiondirection of the leads Lt are formed in the leads Lt.

Because the leads Lt becomes longer as the distance between the drivingtransistors Q1 and the light-emitting elements 2 a increases, the wiringresistance of the leads Lt increases. For this reason, by enlarging thecross-sectional area SA of the leads Lt, an increase in the wiringresistance of the leads Lt is moderated. Consequently, phenomena such asan increase in power consumption and a rise in temperature associatedtherewith can be prevented.

Also, in the light source apparatus (distance measuring apparatus 1) asan embodiment, in the portions (such as SA3, SA5, and SA6 in FIG. 16) ofthe leads Lt, the width in the thickness direction of the wiring layersLy is increased.

With this arrangement, by increasing the width in the thicknessdirection of the wiring layers Ly, the cross-sectional area SA of theleads increases, and an increase in wiring resistance is moderated.Also, by increasing the width in the thickness direction of the wiringlayers Ly to moderate an increase in the wiring resistance, wiringdesign that leaves surplus room in the planar direction of the wiringlayers Ly is possible.

Also, in the light source apparatus (distance measuring apparatus 1) asan embodiment, in the portions (such as SA9, and SA11 in FIG. 17) of theleads Lt, the width in the planar direction of the wiring layers Lt isincreased.

With this arrangement, by increasing the width in the planar directionof the wiring layers Ly, the cross-sectional area SA of the leadsincreases, and an increase in wiring resistance is moderated. Also, byincreasing the width in the planar direction of the wiring layers Ly tomoderate an increase in the wiring resistance, wiring design that leavessurplus room in other wiring layers Ly is possible.

Furthermore, in the light source apparatus (distance measuring apparatus1) as an embodiment, the leads Lt provided in the wiring layers Lyincrease in cross-sectional area (wiring cross-sectional area SA) inlower wiring layers Ly.

The lower the wiring layer Ly, the greater the distance between thedriving transistors Q1 and the light-emitting elements 2 a, and theleads Lt become longer as a result. Consequently, the wiring resistanceof the leads Lt increases. For this reason, by enlarging thecross-sectional area SA of the leads Lt, an increase in the wiringresistance of the leads Lt is moderated. Consequently, phenomena such asan increase in power consumption and a rise in temperature associatedtherewith can be prevented.

In addition, in the light source apparatus (the distance measuringapparatus 1) as an embodiment, the driving section 3 is configured to becapable of individually driving emission operation for eachpredetermined unit of a plurality of the light-emitting elements 2 a(see FIG. 3).

With this configuration, the emission driving current is set to turnemission ON/OFF individually for each light-emitting element or in unitsof blocks acting as multiple light-emitting element groups, for example.

This arrangement achieves a configuration capable of control accordingto the temperature conditions for each predetermined unit ascertained asthe temperature detection value from each temperature sensor 10 a.

Additionally, driving control according to an in-plane temperaturedistribution of the emission section 2 is possible.

With regard to the distance measuring apparatus 1, by controlling thelight-emitting elements 2 a for each predetermined unit, exposure withuniform emission and light energy is possible, and the brightness of theimage of reflected light from the target (subject S) appearing in theimage captured by the image sensor 7 can be made to approach uniformity.With this arrangement, the distance measurement sensing accuracy is alsoimproved.

Further, in the light source apparatus (the distance measuring apparatus1) as an embodiment, an example has been described where the emissionsection 2 emits light in synchronization with the frame period of theimage sensor 7 that receives light emitted by the emission section 2 andreflected by the subject.

With this arrangement, to handle the case of measuring distance byilluminating a subject with light emitted by the emission section andreceiving the light with an image sensor, it is possible to cause thelight-emitting elements to emit light at appropriate timings accordingto the frame cycle of the image sensor.

Consequently, an improvement in distance measurement accuracy may beattained. In addition, a suppression of a temperature rise incorrespondence with the case where a light source apparatus is used asthe light source for measuring the distance to the subject may beattained.

Action and effects similar to the light source apparatus according tothe embodiment described above may also be obtained with a sensingmodule according to such an embodiment.

Note that the above describes an example of a configuration in which theswitch SW is provided for each light-emitting element 2 a to enableindividual control of each light-emitting element 2 a, but in thepresent technology, a configuration enabling the individual driving ofeach light-emitting element 2 a is not essential, but it is sufficientto enable at least individual control for each concurrent emissiongroup.

Additionally, although the above describes an example in which thepresent technology is applied to a distance measuring apparatus, thepresent technology is not limited to being applied to a light source fordistance measurement.

Note that the effects described in this specification are merelynon-limiting examples, and there may be other effects.

9. PRESENT TECHNOLOGY

Note that the present technology may be configured as below.

(1)

A light source apparatus including:

an emission section in which a plurality of vertical-cavitysurface-emitting laser light-emitting elements is arrayed; and

a driving section configured to cause the plurality of light-emittingelements of the emission section to emit light, in which

at least a portion of a region including driving elements in the drivingsection is disposed so as not to overlap with the emission section.

(2)

The light source apparatus according to (1), in which

a chip in which the emission section is formed is mounted onto a chip inwhich the driving section is formed, and at least a portion of theregion including the driving elements of the driving section is disposedso as not to overlap with the light-emitting elements of the emissionsection.

(3)

The light source apparatus according to (1) or (2), in which

the driving section includes a plurality of wiring layers in which leadsfor electrically connecting the driving elements and the light-emittingelements are formed.

(4)

The light source apparatus according to (3), in which

the leads are formed such that a distance between the driving elementsand the light-emitting elements connected to each other is longer inlower wiring layers.

(5)

The light source apparatus according to (4), in which

a plurality of regions including the driving elements is provided in thedriving section.

(6)

The light source apparatus according to any one of (3) to (5), in which

as a length of the leads increases, a portion of increasedcross-sectional area when taking a cross section in a planeperpendicular to an extension direction of the leads is formed in theleads.

(7)

The light source apparatus according to (6), in which

in the portion of the leads, a width is increased in a thicknessdirection of the wiring layers.

(8)

The light source apparatus according to (6) or (7), in which

in the portion of the leads, a width is increased in a planar directionof the wiring layers.

(9)

The light source apparatus according to any one of (6) to (8), in which

the cross-sectional area of the leads provided in the wiring layers islarger in lower wiring layers.

(10)

The light source apparatus according to any one of (1) to (9), in which

the driving section is configured to be capable of individually drivingemission operation for each predetermined unit of a plurality of thelight-emitting elements.

(11)

The light source apparatus according to any one of (1) to (10), in which

the emission section is configured to emit light in synchronization witha frame period of an image sensor configured to receive light emitted bythe emission section and reflected by a subject.

(12)

A sensing module including:

a light source apparatus provided with an emission section in which aplurality of vertical-cavity surface-emitting laser light-emittingelements is arrayed, and a driving section configured to cause theplurality of light-emitting elements to be emitted of the emissionsection to emit light, in which at least a portion of a region includingswitching elements in the driving section is disposed so as not tooverlap with the emission section; and

an image sensor configured to capture an image by receiving lightemitted by the emission section and reflected by a subject.

REFERENCE SIGNS LIST

-   1 Distance measuring apparatus-   2 Emission section-   2 a Light-emitting element-   3, 3A Driving section-   7 Image sensor-   10 Temperature detection section-   S Subject-   B Substrate-   Ch2, Ch3, Ch4, Ch34, Ch7 Chip-   30, 30A Driving circuit-   31 Driving control section-   Q1, Q2 Driving transistor-   SW Switch-   100, 100A Light source apparatus

1. A light source apparatus comprising: an emission section in which aplurality of vertical-cavity surface-emitting laser light-emittingelements is arrayed; and a driving section configured to cause theplurality of light-emitting elements of the emission section to emitlight, wherein at least a portion of a region including driving elementsin the driving section is disposed so as not to overlap with theemission section.
 2. The light source apparatus according to claim 1,wherein a chip in which the emission section is formed is mounted onto achip in which the driving section is formed, and at least a portion ofthe region including the driving elements of the driving section isdisposed so as not to overlap with the light-emitting elements of theemission section.
 3. The light source apparatus according to claim 1,wherein the driving section includes a plurality of wiring layers inwhich leads for electrically connecting the driving elements and thelight-emitting elements are formed.
 4. The light source apparatusaccording to claim 3, wherein the leads are formed such that a distancebetween the driving elements and the light-emitting elements connectedto each other is longer in lower wiring layers.
 5. The light sourceapparatus according to claim 4, wherein a plurality of regions includingthe driving elements is provided in the driving section.
 6. The lightsource apparatus according to claim 3, wherein as a length of the leadsincreases, a portion of increased cross-sectional area when taking across section in a plane perpendicular to an extension direction of theleads is formed in the leads.
 7. The light source apparatus according toclaim 6, wherein in the portion of the leads, a width is increased in athickness direction of the wiring layers.
 8. The light source apparatusaccording to claim 6, wherein in the portion of the leads, a width isincreased in a planar direction of the wiring layers.
 9. The lightsource apparatus according to claim 6, wherein the cross-sectional areaof the leads provided in the wiring layers is larger in lower wiringlayers.
 10. The light source apparatus according to claim 1, wherein thedriving section is configured to be capable of individually drivingemission operation for each predetermined unit of a plurality of thelight-emitting elements.
 11. The light source apparatus according toclaim 1, wherein the emission section is configured to emit light insynchronization with a frame period of an image sensor configured toreceive light emitted by the emission section and reflected by asubject.
 12. A sensing module comprising: a light source apparatusprovided with an emission section in which a plurality ofvertical-cavity surface-emitting laser light-emitting elements isarrayed, and a driving section configured to cause the plurality oflight-emitting elements of the emission section to emit light, in whichat least a portion of a region including driving elements in the drivingsection is disposed so as not to overlap with the emission section; andan image sensor configured to capture an image by receiving lightemitted by the emission section and reflected by a subject.